Discussion:
85 2m4 engine problem
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Hank
2007-07-17 00:42:13 UTC
Permalink
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.

I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank
Les Benn
2007-07-17 16:03:24 UTC
Permalink
Post by Hank
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.
I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank
Hank have you changed the fuel filter?
Hank
2007-07-18 00:55:38 UTC
Permalink
Post by Les Benn
Post by Hank
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.
I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank
Hank have you changed the fuel filter?
Yes fuel filter replaced and checked EGR as well ran it tonight it
runs good when cold but as soon as it get near operating temperature
it runs crapy again ??
Thanks
Hank
Les Benn
2007-07-18 14:51:32 UTC
Permalink
Post by Hank
Post by Les Benn
Post by Hank
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.
I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank
Hank have you changed the fuel filter?
Yes fuel filter replaced and checked EGR as well ran it tonight it
runs good when cold but as soon as it get near operating temperature
it runs crapy again ??
Thanks
Hank
Is it just at operating temp or when you are driving down the road and it
reaches operating temp? What about a vacuum leak? Have you done any checks
to see if you have cracked vacuum lines?
Hank
2007-07-18 21:17:05 UTC
Permalink
Post by Les Benn
Post by Hank
Post by Les Benn
Post by Hank
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.
I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank
Hank have you changed the fuel filter?
Yes fuel filter replaced and checked EGR as well ran it tonight it
runs good when cold but as soon as it get near operating temperature
it runs crapy again ??
Thanks
Hank
Is it just at operating temp or when you are driving down the road and it
reaches operating temp? What about a vacuum leak? Have you done any checks
to see if you have cracked vacuum lines?
Yes runs fine at cold which only lasts a few minutes.
At operating temp it runs crappy.
I replaced a couple of vacuum lines that did not look good.
I do not have a vacuum gage its missing I will pick one up but never
really used it so not sure what to look for.
Hank
Les Benn
2007-07-19 01:34:27 UTC
Permalink
Post by Hank
Post by Les Benn
Post by Hank
Post by Les Benn
Post by Hank
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.
I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank
Hank have you changed the fuel filter?
Yes fuel filter replaced and checked EGR as well ran it tonight it
runs good when cold but as soon as it get near operating temperature
it runs crapy again ??
Thanks
Hank
Is it just at operating temp or when you are driving down the road and it
reaches operating temp? What about a vacuum leak? Have you done any checks
to see if you have cracked vacuum lines?
Yes runs fine at cold which only lasts a few minutes.
At operating temp it runs crappy.
I replaced a couple of vacuum lines that did not look good.
I do not have a vacuum gage its missing I will pick one up but never
really used it so not sure what to look for.
Hank
A good vacuum gauge is soapy water look for bubbles
Hank
2007-07-20 23:43:53 UTC
Permalink
Post by Les Benn
Post by Hank
Post by Les Benn
Post by Hank
Post by Les Benn
Post by Hank
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.
I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank
Hank have you changed the fuel filter?
Yes fuel filter replaced and checked EGR as well ran it tonight it
runs good when cold but as soon as it get near operating temperature
it runs crapy again ??
Thanks
Hank
Is it just at operating temp or when you are driving down the road and it
reaches operating temp? What about a vacuum leak? Have you done any checks
to see if you have cracked vacuum lines?
Yes runs fine at cold which only lasts a few minutes.
At operating temp it runs crappy.
I replaced a couple of vacuum lines that did not look good.
I do not have a vacuum gage its missing I will pick one up but never
really used it so not sure what to look for.
Hank
A good vacuum gauge is soapy water look for bubbles
I put a vacuum gage on it tonight the vacuum presure held stable just
like the book said I also checked the coolent sensor the resistance at
cold and at hot measures fine like the repair guide says. Still no
stored codes in the ECM.
Brian
2007-07-29 22:58:53 UTC
Permalink
Have you checked the exhaust backpressure yet? You could have a clogged
catalytic converter, muffler or collapsed pipe. You can check it at the O2
sensor location. The book mentions that it should be no more than 1-1/4 psi.
That may cause the idle problem as well as loss of power after building up
pressure..unrelated to the temp. It would also cause the temp to increase
faster than usual as the pressure builds. Might be worth investigating. My
first guess would be clogged cat since that is common on older vehicles.
Hank
2007-08-01 00:38:00 UTC
Permalink
On Sun, 29 Jul 2007 17:58:53 -0500, "Brian"
Post by Brian
Have you checked the exhaust backpressure yet? You could have a clogged
catalytic converter, muffler or collapsed pipe. You can check it at the O2
sensor location. The book mentions that it should be no more than 1-1/4 psi.
That may cause the idle problem as well as loss of power after building up
pressure..unrelated to the temp. It would also cause the temp to increase
faster than usual as the pressure builds. Might be worth investigating. My
first guess would be clogged cat since that is common on older vehicles.
Not sure how I can check that out ?
Hank
Brian
2007-08-03 10:04:44 UTC
Permalink
remove O2 sensor and attach a guage there?
ron
2007-08-30 01:42:57 UTC
Permalink
get you an oem vac, that is the problem had it for years before I
figured it out. replaced with junk copy it ran for a while then
problem came back, thought that couldnt be it just replaced it. got
oem and sure enough. oh and it was heat related and will never ever
give you a message! cost like $40 but i would bet my $40 on it!

On Fri, 3 Aug 2007 05:04:44 -0500, "Brian"
Post by Brian
remove O2 sensor and attach a guage there?
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